Department of Chemistry, University of Waterloo, Waterloo, Ontario N2L 3G1, Canada.
J Chem Phys. 2013 Nov 14;139(18):184115. doi: 10.1063/1.4829506.
In this paper, we extend the previously introduced Post-Quantization Constraints (PQC) procedure [G. Guillon, T. Zeng, and P.-N. Roy, J. Chem. Phys. 138, 184101 (2013)] to construct approximate propagators and energy estimators for different rigid body systems, namely, the spherical, symmetric, and asymmetric tops. These propagators are for use in Path Integral simulations. A thorough discussion of the underlying geometrical concepts is given. Furthermore, a detailed analysis of the convergence properties of the density as well as the energy estimators towards their exact counterparts is presented along with illustrative numerical examples. The Post-Quantization Constraints approach can yield converged results and is a practical alternative to so-called sum over states techniques, where one has to expand the propagator as a sum over a complete set of rotational stationary states [as in E. G. Noya, C. Vega, and C. McBride, J. Chem. Phys. 134, 054117 (2011)] because of its modest memory requirements.
在本文中，我们扩展了先前介绍的后量化约束（PQC）方法[G. Guillon、T. Zeng 和 P.-N. Roy，J. Chem. Phys. 138, 184101 (2013)]，以构建不同刚体系统（即球对称和非球对称陀螺）的近似传播子和能量估计器。这些传播子用于路径积分模拟。本文还深入讨论了基本的几何概念。此外，还对密度和能量估计器的收敛特性进行了详细分析，并给出了说明性的数值示例。后量化约束方法可以得到收敛的结果，是所谓的态和求和技术的实用替代方法，因为由于其适度的内存要求，后量化约束方法必须将传播子展开为完整的旋转定态和的和[如 E. G. Noya、C. Vega 和 C. McBride，J. Chem. Phys. 134, 054117 (2011)]。
